Process of making ferric sulphate



July l1, 1933. H. s, MARSH Er Al. A 1,917,945 PROCESS OF MAKING FERRICSULPHATE u Filed Deo. 14, 1928 Ferrous Sup/m@ (5,0504 7,@7 o) Heaz ao400-`0 /L- o make a/vyaraas fer/fou; @da/7a e (@1704) f/ha lZo 60 meshPatented July 11, 1933 UbiTED STATES PATET @F.FIC

S. MARSH AND CARL W. WEESNER, .OF YOUNGSTOWN, OH-IO, ASSIGNGR-S TOSHARON STEEL H001? COMPANY, OF SHARGN, PENNSYLVANIA, A CORPORATION OFPENNSYLVAIA PROCESS OF MAKING FERRIVC SULPHATE Application filedDecember 14, 1928.

This invention reates to a process of producing ferrie sulphate fromferrous sulphate. lt relates more particularly to a process of producingferrie sulphate from ferrous sulphate having water of crystallization.

The accompanying drawing is a flow sheet which illustrates the process.

In Patent No. 1,589,610, granted J une 22, i026 to Henry S. Marsh andRalf S. Cochran for a method of Reclaiming spent pickling solutions,there is disclosed a method of obtaining copperas crystals from thespent pickling solution. The wet copperas crystals obtained inaccordance with the patented process contain seven molecules of water ofcrystallization. These copperas crystals may be heated to a temperatureof 9.120 F. or higher in order to produce dry copperas crystals having'one molecule of water of crystallization.

The present invention has for one of its objects the production offerrie sulphate from dry crystals of ferrous sulphate no matter in whatmanner the dry ferrous sulplate or copperas crystals are obtained. Onemethod of obtaining dry copperas crystals having seven or less thanseven molecules of water of crystallization is by heating the wetcopperas crystals obtained by the patented process above referred to.

Tn accordance with the present invention ferrous sulphate (oopperas)crystals containing water of crystallization are heated to a temperaturesuflicient to drive off all of the water of crystallization and renderthe crystals substantially anhydrous. This may be accomplished byheating to a temperature of 400-6000 F. and preferably by heating to atemperature of about 4500 F. This heating, which renders the crystalsanhydrous, produces a very friable material which can be easily crushed.The friable material is then iinely divided by any grinding means, forexample, by crushing it between two steel rollers having smoothsurfaces. It is preferable to grind the material to a size such that itwill pass through a sieve having meshes to the inch. The ground ferroussulphate is then heated un- Serial No. 326,151.

der oxidizingconditions to a temperature sufficient to convert it intoferrie sulphate and ferrie oxide. This may be accomplished by heating itin a rotary furnace of the open muflle type to a temperature of 850- 925F., preferably about 900 F. If temperatures higher than these areemployed the ferric sulphate tends to decompose, resulting in theformation of an excess quantity of ferric oxide. If lower temperaturesare employed some ferrous sulphate will remain unconverted. Y

The material discharging from the 'rotary furnace contains about ferricsulphate and about 20% ferric oxide, the ferrie oxide having been formedduring the heating step in which the material within the kiln had accessto the oxygen of the air. The material coming from the kiln is thenfurther treated in order to convert the ferrie oxide into ferricsulphate. This may be accomplished by treating the material with asubstance containing a sulphate radical. It is preferred to usesulphuric acid for this conversion. The material discharged from therotary furnace is introduced slowly while stirring into a dilutesolution of sulphuric acid. Since during this addition heat is evolved,it is preferred to cool the mixture by any desired means. If thematerial is added too rapidly to the acid a jellylike mass is formedwhich is very diflicult to control. The addition should, therefore, bemade very slowly with constant stirring and cooling of the mixture sothat a mushy somewhat liquid and flowable mass is obtained which can bemore easily handled and managed than the jellylike mass which would beproduced manner of carrying out our process.

erric sulphate is indicated by the mass changing from a red to a strawor white color. The heating is continued until the mass is thoroughlydry, after which the product is ready for use.

We have described the present preferred It is to be understood howeverthat the process may be otherwise practiced without departing from thespirit of the invention or the scope of the appended claims.

Ve claim:

1. In the process of making ferric sulphate, the steps which compriseheating anhydrous ferrous sulphate in the presence of oxygen to about900 F. to convert it into icrric sulphate and erric oxide, slowlyintroducing the mass into sulphuric acid while stirring, and heating theresulting mass to accelerate the reaction.

2. In the process of making ferrie sulphate, the steps which compriseheating tine ly ground anhydrous ferrous sulphate in the presence ofoxygen to a temperature oi? S- 9250 F. to convert it entirely into erricsulphate and erric oxide, and slowly introducing the resultant productinto sulphuric acid while stirring, and heating the resulting mass toaccelerate the reaction.

3. The process of making erric sulphate from ferrous sulphate havingwater of crystallization, which comprises heating the ferrous sulphateto a temperature of S50-925 F. to convert it entirely into ferricsulphate and ferrie oxide, treating the resultant prod uct withsulphuric acid to transform the ferrie oxide to erric sulphate, andheating the resulting mass to about 500 F. to vaccelerate the reaction.

4. In the process of making erric sulphate, the steps which compriseheating linely ground anhydrous 'iierrous sulphate in the presence ofoxygen to a temperature of S50-9250 F. to convert it into a mixturecontaining about 80% ferrie sulphate and about 20% ferrie oxide, slowlyintroducing the mixture into a. dilute solution of sulphuric acid whilestirring and cooling to convert the ferrie oxide into ferrie sulphate,heating the mixture to about 300-S50o F. to accelerate the reaction, andthereafter continuing tlhe heating until the mass is substantially c ry.

In testimony whereof we have hereunto set our hands.

HENRY S. MARSH. CARL W. VEESNER.

